In accordance with the present invention, the present invention relates generally to joist systems used as structural supports when constructing floors or roofs; and more particularly, relates to a floor joist support system having adjustable joist sections to conform to distance between opposing foundation walls.
In the construction industry, typically, beams and girders are used to provide a structural framework when laying a concrete floor or assembling a roof. Generally, when a basement or ground floor is built, a platform or deck is then secured to the beam framework and the concrete poured over the top of the platform or deck. Once the concrete has set, the girders or joists are typically removed from beneath the new concrete floor, a process which, if not done carefully, can crack or otherwise disturb the new floor. See, for example, Hunnebeck's U.S. Pat. Nos. 2,974,762 and 3,062,340.
Hunnebeck's devices also attempted to provide a means of adjusting girders to vary the length according to the desired span between foundation walls by providing telescoping girder units. Similarly, U.S. Pat. No. 3,078,970 to Black; U.S. Pat. No. 3,029,913 to Liesenfeld; U.S. Pat. No. 4,070,845 to Cody; and U.S. Pat. No. 3,968,616 to Gostling have attempted to provide adjustable trusses or beams for use in concrete scaffolding or as support forms for concrete roofs, decks and roadways, and in combination with decking. While the prior art has contemplated the use of telescoping or otherwise adjustable beams and trusses in floor construction, none discloses a way of utilizing adjustable length beam members as a part of the floor structure with ends of the beams permanently affixed to the foundation wall structures.
Furthermore, the present invention provides a distinct advantage over the above cited prior art devices by not only providing a floor system that may remain as a permanent ground floor in a structure, but in providing a system that employs a joist support member as a floor support beam that can accommodate either telescoping joists or pairs of joists in overlapping relation to one another within a joist support. Because the beam ends are permanently affixed to the foundation walls and also to the joist support itself after the total length of the telescoping joist or cooperating joist pairs is adjusted, the system of the present invention is especially useful in areas where the ground tends to heave or shift, or cannot otherwise be graded to support a ground floor constructed directly thereon. Thus, the present invention provides a suspended floor system suited to these types of environments, and also allows for adjustability of the joists through a joist support to accommodate possible discrepancies between plan measurements and the distances actually encountered during the construction process.